Multiple "When" in Trigger

Hy out there, my question may sound strange but is there a possibility to have more then one WHEN-Condition in a trigger ? I tried out something like this : create trigger example1insert on tab_1 referencing new as not_old for each row when (a=1) (execute spl_1()); when (a=2) (execute spl_2()); I tried out multiple version with changing syntax but there is always a syntax error after the first "when" condition. Any help would be appreciated.